Cigarette and cigarette filter making machine

ABSTRACT

A cigarette or filter making machine has a cut-off device (19) which is driven directly by its own motor (21), pick-up device (22) for monitoring the rotational speed and timing of the cut-off device, and at least one other independent motor (especially a motor 24 driving the garniture tape 15 and/or a motor driving the filter attachment machine) which is driven in synchronization with the cut-off device under the control of the monitoring pick-up device.

Cigarette making machines commonly comprise means for forming a streamof tobacco or other smokable material which is enclosed in a continuouswrapper to form a continuous rod which is then cut at regular intervals.The rod-forming device commonly includes a garniture tape which supportsthe wrapper web while the cigarette filler stream is on the web and isbeing compressed and shaped to the final cross-section, and whichassists in wrapping the web around the filler stream; the edges of theweb are then normally brought together and secured by adhesive. Thefiller stream is commonly trimmed by means of a trimming device beforebeing enclosed in the wrapper web. Examples of such machines are theMolins Mark 8 and Mark 9 cigarette making machines.

Cigarette filter making machines are commonly similar apart from thefact that the filter tow does not require trimming. An example of anexisting filter making machine is the Molins PM5 machine.

In the Mark 8 generation of cigarette making machines, and also in thefilter making machines of the same period, it was common to provide amain shaft which was driven at a speed equalling the number of rods perminute produced by the machine. For example, a machine making 2,000cigarettes per minute would have a main shaft rotating at 2,000revolutions per minute, the cutting device comprising commonly a rotaryarrangement making one cut per revolution.

A more recent trend embodied, for example, in the Mark 9 and PM5machines which are capable of running at speeds of 4,000 rods per minuteor even higher, is to provide a main shaft running at well below themachine speed (i.e. in terms of rods per minute). The cut-off device isthen driven from the main shaft through step-up gearing; and variousother gears with appropriate ratios provide driving connections from themain shaft to the various other driven parts of the machine. By thismeans, the noise of the machine is reduced.

Noise has become an important criterion in the modern generation ofmachines, and machines have been built with cut-off devices having twoblades so as to make two cuts per revolution and so as to rotate at halfthe previous speed. It is also possible to cut double-length rods whichare cut later in the filter-attachment machine; assuming a double-knifecut-off device, this enables the cut-off device to rotate at one quarterthe machine speed in terms of finished rods per minute. However, evenwith such an arrangement, at speeds in excess of 5,000 rods per minute,noise remains a problem; noise is generated by many parts of themachine, including the gearing.

According to one aspect of this invention in a method of making rods ofthe cigarette industry in which a continuous rod is formed and is cut atregular intervals, at least two different devices used in themanufacture of the rods are driven by separate motors, the speed of afirst motor (the "master") being sensed, and the speed of a second motor(the "slave") being controlled so that the second motor runs at a speedhaving a predetermined relationship with the speed of the first motor.

Preferably the speed of the first motor is sensed by generating a pulsedelectrical signal derived directly or indirectly from a rotary part onor associated with the first motor, and the speed of the second motor issensed by generating a pulsed electrical signal derived directly orindirectly from a rotary part on or associated with the second motor.

In a cigarette making machine according to this invention the "master"motor preferably drives the cut-off device including, preferably, themoving parts (if any) of the ledger which supports the rod duringcutting. Other parts of the machine are driven by one or more separate"slave" motors synchronised to the cut-off either as regards speed aloneor as regards both speed and phase.

Various parts of the machine may be driven by separate motorssynchronised to the cut-off. The accuracy with which synchronisationneeds to be achieved varies. For example, the garniture tape drive needsto be accurately controlled so that the rod speed is closely related tothe cut-off speed to produce rods of precisely the required length, butphase synchronisation is not normally needed. A printing device may beincluded to apply an insignia or legend to the wrapper web at regularintervals; the insignia or legend needs to be positioned with somedegree of accuracy close to the end of each finished rod, so thataccurate synchronisation of the speed of the printed drive is needed aswell as fairly accurate phase synchronisation. The trimming device isanother part of the machine which may also have its own independentdrive motor, especially if it is arranged to produce "dense ends" in thestream at regular intervals, i.e. denser portions to form the ends ofthe finished cigarettes.

According to a second aspect of this invention, a machine for makingrods of the cigarette industry includes at least two parts which aredriven by separate motors, means for producing a pulsed electricalsignal at a frequency proportional to the speed of the first motor,means for producing a pulsed electrical signal at a frequencyproportional to the speed of the second motor, and a comparator devicefor comparing the two pulsed signals and for controlling the speed ofthe second motor to maintain a predetermined relationship between thetwo pulse frequencies.

An important possibility which this invention facilitates is the use ofa separate motor to drive the filter attachment machine. This allows thefilter attachment machine to be run on for a short period after themaking machine has stopped producing rods. Thus the completed cigaretterods can all be joined to filters and waste is avoided.

A mechanical drive can be used as an alternative to the above-mentionedarrangement to allow the filter attachment machine to be drivenindependently of the cigarette making machine. Two separate motors maybe fitted respectively to the making and filter attachment machines,with a dog clutch between them to ensure phase synchronisation whereboth are running. However, a preferred arrangement is described belowwith reference to FIG. 3 of the accompanying drawings, using a commonmotor for driving both machines.

Examples of machines according to this invention will now be describedwith reference to the accompanying drawings. In these drawings:

FIG. 1 is a schematic drawing showing a cigarette making machines havinga number of synchronised motors;

FIG. 2 shows a circuit whereby one slave motor can be synchronised to amaster both as to speed and as to phase; and

FIG. 3 shows a mechanical drive arrangement whereby a cigarettemaker/filter attachment combination can be driven independently ortogether by a common motor.

An example of a cigarette machine according to this invention is shownin FIG. 1 which is a diagrammatic drawing. The machine is basically likea Molins Mark 9 cigarette making machine. Tobacco is showered up achimney 10 with the aid of an upward air flow to form a cigarette fillerstream 11 on a suction band 12. The filler stream is then trimmed by atrimming device 13 and is then deposited by the band 12 on a wrapper web14 supported by a garniture tape 15. A tongue 16 compresses the fillerstream to its final cross-section, and a folder 17 secures the web 14around the compressed filler stream to form a continuous cigarette rod18. A cut-off device 19 cuts the continuous rod at regular intervals toform individual rods 20 which are accelerated by a suction wheel 30(e.g. like the wheel 3 described in out British patent specification No.1,313,133) and then enter into the flutes of a fluted drum 31 formingpart of a filter attachment machine which may, for example, be a MolinsPA8 machine.

The general arrangement for forming the cigarette filler stream is inaccordance with the invention described in British patent specificationNo. 916,141. The trimming device 13 is generally in accordance with theinvention described in British patent specification No. 881,024 asmodified in accordance with specification No. 1,314,825. The cut-offdevice 19 may be in accordance with British patent specification No.1,238,458, i.e. may comprise a disc or cylinder with an inclined blade,the axis of rotation of the disc being inclined to the cigarette rod sothat the blade is at right angles to the rod during cutting.

The cut-off device is driven directly by a motor 21. The drive may bedirect in the sense that it comprises a straight coupling;alternatively, a slight step down or step up gear drive may be used ifit is convenient to do so. The same motor may be arranged to drive aledger for supporting the rod during cutting, e.g. a rotary ledger asdescribed in British patent specification No. 1,238,458 or No.1,332,689.

Mounted on or associated with the motor 21 there is a pulse generator 22for indicating the speed and phase (rotational position) of the cut-offmotor. The pulse generator may be an optical device or may include amagnetic pick-up; such devices are available as bought-out items.Alternatively, the pulse generator may monitor the speed and phase ofthe cut-off device itself.

A control console 25 receives signals from the pick-up device 22 andcontrols the speed and rotation of various independent motors so as tosynchronise or "slave" those motors to the cut-off drive motor 21."Synchronise" in this context does not mean that the motors all need torun at the same speed. On the contrary, the speed of each slaved motorrelative to the speed of the cut-off motor 21 is preferably adjustable.

In particular, the control console 23 controls a motor 24 driving a drum25 around which the garniture tape 15 passes and by which the tape isdriven. Furthermore, as shown in the drawing, a motor 26 driving thetrimming device 13 is controlled by the console 23, as is a motor 27driving a printer 28. Finally, the drawing shows diagrammatically amotor 32a driving a pulley 32 around which the suction tape 12 passes,which motor may also be controlled by the console 23.

Other motors may also be driven in a synchronised fashion via thecontrol console 23. For example, a motor slaved to the cut-off drive maybe provided to drive the filter-attachment machine by which filters areattached to the cigarettes 20. This allows the filter attachment machine(which is commonly driven from the cigarette making machine) to bemaintained in operation for a short time after the maker is stopped, soas to allow all the materials (filters, cigarettes and tipping paper) tobe used up before the filter attachment machine is stopped; the run-downsequence for the filter attachment machine is preferably programmed sothat this happens automatically. In the arrangement shown in thedrawing, the accelerator wheel 30 or an equivalent device is perferablydriven by the motor driving the drum 31 and the other parts of thefilter attachment machine; the timing of that motor with respect to themotor 21 is then not very critical, an accuracy of up to about 10% beingpossibly acceptable.

The cut-off motor 21 may be in any convenient form, preferably withprovision for speed control. However, each of the motors which is slavedto the motor 21 needs to be in a form which can be controlled with acertain degree of accuracy (not necessarily the same for each motor)both as to its speed and, in the case of at least the motors 26 and 27and the filter attachment drive motor, also as to its phase. Motors areavailable for that purpose, for example, as described in patentspecification Nos. 1,331,601, 1,375,824 and 1,382,807.

FIG. 2 is a block diagram showing how one of the slaved motors may becontrolled in the system shown in FIG. 1.

A pulsed electrical signal at a frequency proportional to the speed ofthe cut-off is picked up from a rotating part 40 which may be part ofthe cut-off or of its drive motor. The pulses are fed to a device orcircuit 42 (of known design) which produces an output in the form ofpulses at a frequency bearing a predetermined ratio in relation to thefrequency of the pulses fed into the device 42; the output frequencyfrom the device 42 is preferably adjustable. The device 42 may be a ratemultiplier, e.g. a BCD rate multiplier such as type CD 4527B made byRCA, or a binary rate multiplier such as the RCA type CD 4089B. Anotherpossibility is that the device 42 may be a variable divider circuit,e.g. a COS/MOS presettable Divide-by-N counter such as the CD 4018A typemade by RCA, or a cascade of such devices. Alternatively amicroprocessor or other form of computer may be programmed to provide anequivalent mode of operation.

The pulsed output from the device 42 is fed to a rate meter circuit 44(of known design) which produces a D.C. output voltage proportional tothe input pulse frequency. This output voltage is applied to an analoguecomparator device 46.

The slaved motor 48 (which in this example is required to besynchronised as to speed and phase) drives a rotary part 58 serving as apulse generator producing a pulsed output which is fed by line 52 to thecomparator device 46 via a rate meter 47. The device 46 compares thevoltages respectively from the two ratemeters and produces an output toa high-gain amplifier 54 responsive to the voltage difference or to atime integral of the difference. The output of amplifier 54 governs thespeed at which the motor 48 is driven, e.g. by controlling the currentin the armature or field windings if the motor 48 is a D.C. motor. Thusthe motor 48 is driven at a speed bearing a fixed relationship with thespeed of the cut-off.

The pulsed output from the device 42 is also fed to a phase comparatorcircuit 56 (of known design), which circuit also receives a pulsed inputfrom the line 52. If the pulses received by the phase comparator are outof phase, the comparator 56 produces an output which is fed to thecomparator 46 and tends to increase or decrease the speed of the motor48 (whichever is necessary) until the pulses are synchronised as totheir phase.

A line 57 transmits the pulsed signal from the rotary part 40 toadditional circuits for controlling motors driving other parts of themachine.

The pulse frequency transmitted by line 52 may also be modified by meansof a rate multiplier or other frequency-changing device such as any oneof those described above with regard to the device 42. In that case thedevice 42 may be omitted; but it might be convenient nevertheless tokeep it so as to obtain the greatest possible flexibility in regard toadjustment of the relative speeds of the respective parts of themachine.

In the simplest case, the parts 40 and 58 may be arranged to producepulses at the same frequency when rotating at the desired relativespeeds. For example, if the motors driving the parts 40 and 58 arerequired to rotate at speeds having a ratio of 2:1, the parts 40 and 58may comprise optical gratings (with associated optical pick-offs), thepart 58 having twice as many circumferentially spaced grating elementsas there are on the part 40. If there is a need to alter the relativespeeds, the part 40 or 58 may be replaced by a part having a differentnumber of grating elements.

It will be understood that the voltage output of the rate meter 44 isproportional the required speed of the motor 48, while the voltageoutput of the rate meter 47 is proportional to the actual speed of themotor 48. If precise speed control is required then phase comparison andcorrection may be provided (e.g. as described above) even if phasecorrespondence between the parts of the machine driven by the two motorsis not in itself necessary, for example in the case of the garnituretape. Phase correction eliminates the possibility of any slight drift inthe speed relationship since such a drift would naturally also affectthe phase relationship between the respective pulses. In the case of thegarniture tape, pulses may be generated by a rotary part which is, forexample, on or part of the drum 25 or on idler pulley 25A on the tensionside of the drum; alternatively, the tape 15 itself may be marked atregular intervals, e.g. by an additional weft thread, and the marks canbe sensed to produce pulses.

In the place of the rate meter 47 it is possible to provide the motor 48with a tachometer for generating a voltage proportional to the speed ofthe motor 48 to be fed into the comparator device 46. This appliesparticularly if phase correction is not needed, for example in the caseof the hopper of a cigarette making machine.

Where the load of the slaved motor 48 is relatively light, e.g. in thecase of the motor 26 (FIG. 1) driving the trimmer, a stepping motor maybe used.

Instead of one motor being the master to which all the others are"slaved", it is possible to have chain of command. For example, themotor 21 may be "slaved" to the motor 26 (which motor may also drive theband 12), and the motor driving the filter attachment machine may be"slaved" to the motor 21.

In the case of a filter making machine, there may be one motor (amaster) driving the garniture tape and the moving parts (rollers etc.)of the equipment feeding the filter tow to the garniture, and thecut-off may be driven by a second motor "slaved" to the first motor.

FIG. 3 shows a mechanical connection whereby a filter attachment machinemay be driven by the same motor as a cigarette making machine, withprovision for continuing the drive to the filter attachment machine fora short period after the drive to the cigarette making machine hasceased.

A drive motor 70 is mounted on one end of the cigarette making machine71. At opposite ends of the motor 70 there are two eddy currentcouplings 72 and 73 respectively having output shafts 74 and 75; thesecouplings may, for example, be Heenan couplings. These shafts carrypulleys 76 and 77 which drive pulleys 78 and 79 on further shafts 80 and81 via belts 82 and 83.

The shaft 80 drives at least part of the cigarette making machine andalso drives a further shaft 84 via spur gears 85 and 86 and bevel gears87 and 88. A shaft 89, which is the drive shaft for the filterattachment machine, is capable of being driven by the shaft 84 via aunidirectional dog coupling 90 which couples the shafts 83 and 88 onlywhen they are in one or more (e.g. four) predetermined positions withrespect to one another. By this means, the phase of the shaft 89 issufficiently predetermined with respect to the cigarette making machine,and this allows successive cigarette rods to be received in successiveflutes of the fluted drum 31 shown in FIG. 1.

The dog coupling 90 may, for example, be a ball-drive coupling such asthat made by GIB Precision Ltd.

The shaft 81 carries a bevel-gear 91 which meshes with a bevel-gear 92on the shaft 89.

The drive ratio provided by the pulleys 77 and 79 and the belt 83 issuch that, when the coupling 73 is engaged, it tends to drive the shaft89 at a speed which is approximately 1% slower than the shaft 84.

The operation of the machine is as follows. When thecigarette-maker/filter attachment combination is started, both thecouplings 72 and 73 are initially engaged. Therefore the shaft 89driving the filter attachment machine rotates initially slightly moreslowly than the shaft 84, which slowly catches up until the dogs of theclutch 90 engage so as to drive the shaft 89 in the desired phaserelationship with the shaft 84 and at the same speed. By this means, theinitial load in starting the filter arrangement machine does notnormally have to be borne by the driving parts of the dog clutch 90 asthey engage one another; instead, the dogs can engage more gently, i.e.with a 1% speed differential.

Shortly after the combination is switched on (allowing sufficient timefor the dogs of the clutch 90 to engage), the current energising thecoupling 73 is switched off. During continuing operation the shafts 81and 75 merely idle.

When the cigarette making machine is required to stop, the coupling 72is de-energized, and at the same time the coupling 73 is energised. Thisallows the filter attachment machine to continue to be driven (atapproximately 1% below full speed) while the making machine slows downand eventually stops. The filter attachment machine may be programmed torun long enough to feed through it all the cigarettes which it hadalready received from the making machine when the making machine startedits run down procedure. In other words, all the cigarettes received fromthe making machine are joined to filters (thus avoiding any waste ofcigarettes), after which the coupling 73 is de-energised to stop thefilter attachment machine.

It should be appreciated that a cigarette making machine normally doesnot make satisfactory cigarettes during the run down procedure.Therefore it is usual for the cigarette rod to be deflected from itsnormal path as soon as a stop signal for the machine is emitted to startthe run down procedure. At that point in time, there are already asignificant number of satisfactory cigarettes in the filter attachmentmachine, and the present invention enables those cigarettes to be joinedto filters, thus avoiding any waste.

The filter attachment machine may be provided with a "slow" buttonwhich, when pressed, energizes the coupling 73 and causes the motor 70to run slowly to allow the operation of the filter attachment machine tobe checked in slow motion without driving the cigarette making machine.

For the purpose of phase synchronisation in FIG. 1 or FIG. 2, e.g. toensure that the cut-off cuts the rod through the "dense end" portions,the pulse generator 40 (FIG. 2) may have one or more "master" marks toidentify the precise rotational position of the cut-off. Instead ofphase synchronisation being achieved by comparing the phase of twopulsed signals (which need to be at the same frequency for thispurpose), it is possible to use a resolver (of known design) powered byan oscillator to control the "slave" motor in response to pulsesreceived from the pulse generator 40, the resolver being driven directlyor indirectly by the slave motor; in this case (and also in a pulsecomparison system) the basic speed control may be achieved by means of atachometer driven by or incorporated into the slave motor as describedabove.

The phase of the motor driving the trimmer in the case of a "dense end"system may be subject to control by a nucleonic scanning head, e.g. theMolins MAID, which detects the positions of the "dense end" portions inthe continuous cigarette rod. By this means the positions of the "denseend" portions of the rod can be properly set in relation to the ends ofthe finished cigarettes in spite of process variations (e.g. due tospeed changes of the machine as a whole) tending to displace the "denseends".

In the case of the filter attachment machine, instead of its motor beingsynchronized with the cut-off motor, it may be sychronized with pulsesemitted by a device detecting the gaps between successive rods as aresult of acceleration by the accelerator wheel 30 (FIG. 1). Thegeneration of such pulses is described in our British patentspecification Nos. 1,066,056 and 1,320,151.

In the case of a filter making machine, the filter tow is commonly fedtowards the garniture by a tow-opening system including a succession ofpairs of driving rolls. Each pair of rolls may be driven by a separatemotor synchronized electronically with a motor driving the garniture orcut-off, with automatic control of the relative speeds to control, forexample, the amount by which the tow is stretched, thus controlling thepressure drop characteristics of the completed filters. Alternatively, asingle motor may be used to drive the garniture tape and all the rolls,though in this case each pair of rolls is preferably driven via avariable-speed gearbox and is monitored as to its speed relative to thegarniture or to another pair of rolls (e.g. by means of a pulse systemas described above) and is controlled as to its speed in response topressure drop measurement or some other process control measurement.

For the purpose of electronically controlling the slave motor withregard to phase in any of the above examples, the motion of the slavemotor (or of a part driven thereby) may be translated into a change ofphase between two alternating electrical signals, for example by meansof a resolver, using the pulsed signal from the master motor as thereference which is converted directly or indirectly into a phaseanalogue of the required motion of the slave. By this means, therequired motion of the slave is compared with the actual motion, and thecontrol signal to the slave motor is varied accordingly.

We claim:
 1. A method of making rods of the cigarette industry in whicha continuous rod is formed with the aid of a garniture tape and is cutat regular intervals by a rod cutting device to produce separate rodportions, the improvements comprising driving the rod cutting device bymeans of a first motor which determines the speed of production ofdiscreet rod portions by said rod cutting device, driving the garnituretape by means of a second motor, and automatically controlling the speedof said second motor in response to the rate at which separate rodportions are cut from the continuous rod by said rod cutting device. 2.A method according to claim 1, in which the speed of the first motor issensed by generating a first pulsed electrical signal derived directlyor indirectly from a rotary part on or associated with the first motor,and the speed of the second motor is sensed by generating a secondpulsed electrical signal derived directly or indirectly from a rotarypart on or associated with the second motor.
 3. A method according toclaim 2 in which each of the first and second pulsed signals isconverted into a D.C. voltage proportional to the frequency, and inwhich the relative values of the two D.C. voltages are used to controlthe speed of the second motor so as to maintain the voltage relationshipsubstantially constant.
 4. A method according to claim 2 or claim 3 inwhich equal pulse frequencies are generated when the devices drivenrespectively by the two motors are operating at their desired speedsrelative to one another, and in which control is exerted on the secondmotor to bring the pulses substantially into phase with one another. 5.A method according to claim 4 in which the equality of pulse frequenciesis achieved by modifying the pulse frequency of the signal received fromat least one of the rotary parts.
 6. A machine for making rods of thecigarette industry comprising means for forming a continuous rodincluding a garniture tape, a rod cutting device for cutting thecontinuous rod at regular intervals to produce separate rod portions, afirst motor for driving the rod cutting device, a second motor fordriving the garniture tape, and control means for controlling the speedof the second motor in response to the rate at which rod portions arecut from the continuous rod by the rod cutting device.
 7. A machineaccording to claim 6, including first means for producing a pulsedelectrical signal at a frequency proportional to the speed of the firstmotor, including means said control means being responsive to the pulsedsignal for controlling the second motor.
 8. A machine according to claim7 in which the control means comprises second means for producing apulsed electrical signal at frequency proportional to the speed of thesecond motor, and a comparator means for comparing the two pulsedsignals and for controlling the speed of the second motor to maintain apredetermined relationship between the two pulse frequencies.
 9. Amachine according to claim 8 in which said first and second means eachinclude means for producing pulsed signals which are at the samefrequency and in which said comparator means includes means forcomparing the phases of the two signals and for controlling a powersupply to the second motor to keep the pulsed signals substantially inphase with one another.
 10. A machine according to claim 8 or claim 9 inwhich said control means includes means for processing at least one ofthe pulsed signals by an electronic device whereby the pulse frequencyis modified.
 11. A machine according to claim 10, in which the means forproducing a pulsed signal from at least one of the motors includes meansfor altering the frequency of the pulses for a given speed of rotationof the associated motor, whereby the predetermined speed relationship ofthe two motors can be altered.
 12. A machine according to claim 11 inwhich at least one of the pulsed signals is generated with the aid of arotary part which is readily replaceable whereby a different rotary partcan be substituted to produce pulses at a different frequency for agiven speed of rotation of the associated motor.
 13. A cigarette makingmachine according to claim 12 having a cut-off device driven by thefirst motor, the second motor being arranged to drive the filterattachment machine, garniture tape, hopper, trimmer or printer, or acombination of those devices.
 14. A cigarette making machine accordingto claim 13 in which a number of independent motors are arranged todrive different parts of the machine and are synchronised to therod-cutting device.
 15. A machine according to claim 3, including secondmeans for generating a pulsed electrical signal at a frequencyproportional to the speed of the second motor, and means for convertingthe respective pulsed signals from said first and second means into D.C.voltages proportional to the respective frequencies of the pulsedsignals, said control means including means for controlling the speed ofthe second motor to maintain a substantially-constant relationshipbetween said D.C. voltages.